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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

364

CERESINE

SCOPIC DETECTION. This is effected by treating a little of the substance
with hot alcohol, allowing to cool, filtering, and evaporating a few drops
of the filtrate on a slide. A crystalline appearance of the
residue under the microscope indicates the presence of a
considerable proportion of paraffin wax.

(b) DETECTION AND DETERMINATION BY MEANS OF SOL-
VENTS (by Armani and Rodano's method) 1: This method is
based on the different solubilities of paraffin wax and
ceresine in a mixture of absolute alcohol and benzene in
equal proportions.

Use is made of the apparatus represented in Fig. 50 and
consisting of a simple test-tube closed by a stopper chan-
nelled to admit air and with a thermometer divided to 0-5°
passing through it'; the tube is surrounded by a second
larger one and by a glass cylinder on a foot. The test-tube
containing o-i gram of the product is dissolved in 10 c.c. of
the hot solvent, is placed in position and allowed to cool
slowly, the temperature being noted at which the precipi-
tation of the dissolved substance takes place ; this is shown
by the appearance of either a turbidity or, with pure paraffin
wax or ceresine, a slight crystalline layer. Since there is a
difference of 25° between the temperature of precipitation of
paraffin wax (25°) and that of ceresine (50°), the presence
FlG 50 of even small proportions of paraffin wax may be ascer-
tained, while the percentage may be estimated approximately
by means of the following table :

Paraffin Wax.
	Ceresine
	Temperature of
	Paraffin Wax.
	Ceresine.
	Temperature of

/o
	/o
	Precipitation.
	o/ /o
	o/ /o
	Precipitation,

O
	• IOO
	50°
	7°
	3°     f.
	40°

10
	90
	48
	75
	~5
	38

20
	80
	47-5
	80
	20
	36-5

30
	70
	47
	90
	10
	30

40
	60
	44'5
	95
	5
	27

5°
	50
	43
	IOO
	—
	25

60
	4°
	4i-5
	
	
	

4.  Detection of Resins and Fatty Acids.—See Paraffin Wax, 4.

5.  Detection of Carnauba Wax.—See Paraffin Wax, 5.

6.  Detection of Goal-tar Colours.-—See Paraffin Wax, 6.

7.  Detection of added Mineral Matter.—This may be talc, kaolin,
gypsum, etc., and is detected by dissolving the product in benzine and
examining the residue by the ordinary analytical methods.

*

* *

Refined ceresine should be white or faintly yellow, neutral and free from
suspended impurities and should not render sulphuric acid appreciably brown.

1 Ann. Labor. cMm. centrals Gabelle, Vol. VI, p.  109.g between 60° and 66° as a mixture